I read an interesting article the other day which hinted that the purpose of sleep may be to reset synapses by reversing the direction of energetic flow within the neurons, thereby refreshing them for new input the next day. "Fields&#39;s team at the National Institutes of Child Health and Development in Bethesda, Maryland, built on an earlier observation that during sleep (or even when just chilling out), neural signals travel the "wrong way" in cells of a critical region of the hippocampus, the brain structure involved with forming some types of new memories. The new study by Fields demonstrates, in a lab dish, that this reverse trafficking functions as a form of "editing," a physical paring back of inessential parts of a brain cell to ensure that you don&#39;t forget what you learned the previous day. Specifically, electrical signals in the CA1 area of the hippocampus reverse direction like the opposite flow of cars during the evening rush hour. The spiking electrical pulses move up instead of down the long extensions of nerve cells known as axons. The train of spikes pass through the cell body where the nucleus resides before reaching the ends of thousands of tiny branching tendrils called dendrites. Upon arrival, the signals act as dimmer switches that cause neurons to fire less strongly when they receive chemical signals from other neurons across the small gaps known as synapses—in neurospeak, the synaptic strength diminishes. "That allows you to learn the next day because you haven&#39;t saturated your synapses," Fields says. During this synaptic tuneup, some of the synapses disappear as part of a process that helps integrate the sights and sounds of the past day into memory, a process that involves blotting out irrelevant detail and "refreshing" synapses to better absorb the sensory onslaught of the coming day." <a href='https://blogs.scientificamerican.com/talking-back/sleep-hits-the-reset-button-for-individual-neurons/'>https://blogs.scientificamerican.com/talking-back/sleep-hits-the-reset-button-for-individual-neurons/</a>